Answer:
Pendulum B
Step-by-step explanation:
The time period of a pendulum is given by :
![T=2\pi\sqrt{(L)/(g)}](https://img.qammunity.org/2020/formulas/physics/college/lun28mnzbjnegq9csn8us6sxelkuyasyu2.png)
Case 1.
Mass, m = 200 g = 0.2 kg
Length of string, l = 1 m
Time,
![T_1=2\pi\sqrt{(1\ m)/(9.8\ m/s^2)}](https://img.qammunity.org/2020/formulas/physics/college/s7xrrpnrhd0q02d19ypuleiz4gp2kkdcih.png)
T₁ = 2.007 Seconds
Since,
![f=(1)/(T_1)](https://img.qammunity.org/2020/formulas/physics/college/sleru0n1o9o7i4gsxak9nmmyv0ee137bvx.png)
![f_1=(1)/(2.007)](https://img.qammunity.org/2020/formulas/physics/college/fdm97bpx77zpsdp8rek9qskluboyzj6glh.png)
f₁ = 0.49 Hz
Case 2.
Mass, m = 400 g = 0.4 kg
Length of string, l = 0.5 m
Time,
![T_2=2\pi\sqrt{(0.5\ m)/(9.8\ m/s^2)}](https://img.qammunity.org/2020/formulas/physics/college/gur2yc0uk8u7kosdo7d8op2hqbju90wo60.png)
T₂ = 1.41 seconds
![f₂=(1)/(T_2)](https://img.qammunity.org/2020/formulas/physics/college/4c2r84sgvni6mclwksz1y4a35v2mq6oo4q.png)
![f₂=(1)/(1.41)](https://img.qammunity.org/2020/formulas/physics/college/f08ztum6zbj36vhiaoel7lj544rr7bm5om.png)
f₂ = 0.709 seconds
Hence, pendulum B have highest frequency of vibration.